ACID AND BASE DIFFUSION IN CHEMICALLY AMPLIFIED DUV RESISTS

In order to clarify the photogenerated acid diffusion in resist film, the diffusion behavior of acid. as well as the role of additional base component was investigated in tert-butoxycarbonyl (t-BOC) protected t ype chemically amplified positive deep ultraviolet (DUV) resists. The resists consisted of t-BOC protected polystyrene as a base resin, 2,4- dimethylbenzene sulfonic acid derivative as a photoacid generator (FAG ) and N-methyl-pyrrolidone (NMP) as an additional base component. Acid diffusion coefficient was suppressed by the addition of base componen t. Moreover, the change of base concentration corresponded directly to the lithographic performance, such sensitivity, resolution capability and resist profile, especially T-topping formation. Based on the expe rimental analysis, the clear relationship between acid diffusion lengt h and additional base was obtained.